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TDC7200: Time and calibration register values range

Denge
Prodigy 90 points
Part Number: TDC7200

Hello All,

I'm running the TDC7200 @ 16 MHz and have some questions about the Time1 and Time2 registers: as they are only started on the rising flank of the start and stop and related to the clock, they barely change and the maximum value is maximum one clock cycle. Is this reasoning correct?

 Is a similar reasoning also valid for the calibration registers but than without taking into account the start and the stop?

Greetings.

  • 0
    TI__Mastermind 21340 points

    Hello Denge,

    Thanks for posting to the sensors forum! Please let me know if I misunderstood your question.

    If using measurement mode 1, the TIMEn registers reflect the number of times the devices internal ring oscillator wraps, meaning it counts the amount of times the ring oscillator reaches its max allowable count and begins to count again. So the value stored in those registers is not value is not one clock cycle but one count cycle of the ring oscillator. But you are correct that the count does not begin until the device receives the rising edge for the START and will end the count once the designated number of STOPs have been received. The TIMEn registers are dependent on the length of measurements you are making so if you are making small measurements then you will only see small changes to the TIMEn registers. 

    The calibration user a two-point calibration system by sampling a single external clock period as the first measurement and then the second measurement takes the amount of external clock periods configured in by CALIBRATION2_PERIODS register. As far as how these values are calculated and if they use the same ring oscillator method as the TIMEn registers I am not sure. 

    Best,

    Isaac